The catalysts for preparing light olefins by catalytic cracking or pyrolysis with petroleum hydrocarbons as feed stocks comprise three types: the first type is supported metal catalysts with oxides as substrates such as the catalysts disclosed in U.S. Pat. No. 3,541,179, U.S. Pat. No. 3,647,682, DD225,135, and SU1214726, which use SiO2, Al2O3 or other oxides as substrates to support metal elements of Groups IIB, VB, VIIB, and VIIIB. This kind of catalysts are merely suitable for the preparation of light olefins by the catalytic cracking of light feed stocks (boiling range <220° C.). The second type is composite oxide catalysts such as the catalysts disclosed in U.S. Pat. No. 3,725,495 and U.S. Pat. No. 3,839,485, which use ZrO2 and/or HfO2 as main components and contain active alumina, at least one component selected from Cr2O3, MnO, and Fe2O3, and at least one component selected from oxides of alkali metals or alkali earth metals, and the catalyst disclosed by DD152,356, which uses amorphous SiO2.Al2O3 as the catalyst for cracking hydrocarbon oils to prepare light olefins. The third type of catalysts is the zeolites containing catalysts, especially MFI-structured zeolite (five-member ring high silica zeolite) containing ones. This type of catalysts can be used alone or as catalytic cracking additive.
JP60-222428 discloses a process for preparing C2−-C4− by catalytically cracking C5-C25 parafins at 600-750° C. using a catalyst containing ZSM-5 zeolite and Al2O3.
CN1205306C discloses a catalyst for preparing light olefins by cracking petroleum hydrocarbons, which catalyst contains 0-70 wt. % of clay, 5-99 wt. % of inorganic oxides and 1-50 wt. % of zeolites based on the weight of the catalyst, wherein said zeolite is 25-100 wt % of MFI-structured zeolite and 0-75 wt. % of Y-zeolite, characterized in that said MFI-structured zeolite contains phosphor and a transition metal M and has an anhydrous chemical formula of (0-0.3)Na2O.(0.3-5) Al2O3.(1-10)P2O5.(0.7-15)MxOy.(0-10)RE2O3.(70-98)SiO2 based on the mass of the oxide, wherein M is one or two metals selected from Fe, Co, Ni, Cu, Zn, Mo, and Mn.
CN1069016A discloses a process for preparing ethylene by cracking heavy petroleum hydrocarbons at 650-900° C. using a catalyst containing 30-90 wt. % of SiO2, 20-70 wt. % of Al2O3, 0.5-30% by weight of oxides of alkali metals or alkali earth metals, and 1-30 wt. % of faujasite.
CN1093101A discloses a cracking catalyst for producing light olefins, which catalyst consists of 0-70% of clay, 5-99% inorganic oxides, and 1-50% zeolites (based on the weight of the catalyst), wherein the zeolite is a mixture of 0-25 wt. % of REY or high silica Y-zeolite and 75-100 wt. % of five-member ring high silica zeolite containing phosphor and rare earths.
CN1048428C discloses a catalyst for converting petroleum hydrocarbons to light olefins, which catalyst consists of 0-70 wt. % of clay, 5-90 wt. % of inorganic oxides and 10-35 wt. % of zeolites, wherein the zeolite consists of 20-75 wt. % of five-member ring high silica zeolite containing phosphor and rare earths, 20-75 wt. % of high silica Y-zeolite, and 1-25 wt. % of Y-zeolite containing rare earths.
CN1222558A discloses a catalyst for preparing light olefins by catalytic pyrolysis, which catalyst has the following composition (based on the weight of the catalyst): 10-70 wt. % of clay, 5-85 wt. % of inorganic oxides and 1-50 wt. % of zeolites, wherein the zeolite is 0-25 wt. % of Y-zeolite and 75-100 wt. % of five-member ring high silica zeolite containing phosphor and aluminum or magnesium or calcium, and said high silica zeolite is ZSM-5, ZSM-8 or ZSM-11 type zeolite containing 2-8% phosphor and 0.3-3% aluminum or magnesium or calcium (in terms of oxide) with a silica/alumina ratio of 15-60.
CN1069682C discloses a pillared interlayered clay catalyst for preparing ethylene, propylene, and butene by the catalytic pyrolysis of heavy oils, which catalyst consists of 30-75 wt. % of aluminum cross-linked pillared interlayered clay, 10-40 wt. % of inorganic oxide binders containing aluminum or silicon or zirconium, 0-30 wt. % of high silica zeolite with the five-member ring structure, 0-10 wt. % of a modifying component selected from magnesium, aluminum, phosphor, tin, polyethylene glycol or their mixture, and 0-50 wt. % of clay of the kaolin family.
CN1660967A discloses a catalyst for increasing the yield of ethylene and propylene by catalytic pyrolysis, which catalyst contains 7-70 wt. % of clay, 3-70 wt. % of mesopore silica-alumina materials, 5-80 wt. % of inorganic oxides, and 5-60 wt. % of MFI-structured zeolite
CN1354224A discloses a catalytic cracking catalyst for producing gasoline rich in isomeric alkanes, propylene, and isobutane, which catalyst consists of 0-70 wt. % of clay, 5-90 wt. % of inorganic oxides, and 1-50 wt. % of zeolites based on the weight of the catalyst, wherein said zeolite is a mixture of (1) 20-75% high silica Y-zeolite having a silica/alumina ratio of 5-15 and containing 8-20 wt. % of rare earths in terms of RE2O3 and (2) 20-75% high silica Y-zeolite having a silica/alumina ratio of 16-50 and containing 2-7 wt. % of rare earths in terms of RE2O3 and (3) 1-50% β-zeolite or mordenite or ZRP-zeolite based on the zeolite weight. By using this catalyst, the content of isomeric alkanes in gasoline can be increased together with the production of propylene and isobutane being increased.
CN1566267A discloses a catalytic pyrolysis process for preparing ethylene and propylene, which comprises introducing a preheated petroleum hydrocarbon feed stock into a lift pipe reactor, contacting the feed with a hot catalyst containing a five-member ring high silica zeolite, conducting reaction under catalytic pyrolysis conditions, separating the reaction products and spent catalyst. The reaction products are conveyed to the subsequent separation system for product separation, and the spent catalyst is returned to the reactor after being stripped and regenerated for recycle, wherein said five-member ring high silica zeolite contains phosphor and transition metals.
CN1043520A discloses a cracking catalyst, the substrate of which is 0-70 wt. % of clay and 5-99 wt. % of inorganic oxides, and the active component is a mixture of 1-50 wt. % of ZSM-5 and Y-type molecular sieve. In the active component, ZSM-5 accounts for 75-100% by weight and Y-type molecular sieve accounts for 0-25%.
CN1508223A discloses a hydrogenation catalyst wherein the substrate contains alumia, active component comprises molybdenum and/or W and Ni, the pore of a size of 2-6 nm accounts for 70-90% of the total pore volume.
The content of macropores in the prior art catalysts is low, so these catalysts show an insufficient capacity for cracking heavy oils when used in catalytically cracking heavy oils and provide low yields when used for preparing light olefins and propylene by catalytic cracking.